<!DOCTYPE html>
<html lang="en" xmlns="http://www.w3.org/1999/html">


<head>
    <meta charset="UTF-8">
    <title>你好</title>
    <style type="text/css">
        .content {
            background-color:cornflowerblue;
            position: absolute;
            /* 水平居中 */
            left: 50%;
            width: 30%;
            margin-left: -15%;
            /* 垂直居中 */
            top: 50%;
            height: 30%;
            margin-top: -15%;
        }
    </style>
</head>

<body>
<div class="content">
    <br>
    <br>
    <br>
    <input type="button" value="下载">
    </p>
    </p>
    </p>
    </p>
    <input type="file" value="上传">
</div>
</body>

</html>